why does buying a cloth armor and ruby crystal mean towers do nothing???

hmm they do physical damage... therefore having HEALTH and ARMOR REDUCES THE DAMAGE OUT PUT THAT THEY HAVE

it has been that way for a long while

Honestly, it doesn't.

HOWEVER, it's like this: 23 Armor = 19% Physical damage reduction 38 Armor = 27% Physical damage reduction 123 Armor = 55% Physical damage reduction

The more armor you get, the less the armor means. So the less armor you have, the more each armor item bought means.

So when you have a champ buy a tiny bit of armor, it's going to mean a lot more than when they buy a lot of armor. (Longer-run.) Combine that with the flat health increase to endure actual dps, that health is going to stretch a lot longer.